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T O P I C R E V I E W

rasorenson

If Apollo 8 had missed it's lunar orbit insertion burn, or if any Apollo ended up in an abnormal orbit, whether lunar or far flung earth orbit, there must have been a set of parameters for the outside capabilities of the service module's SPS engine to make course corrections for a return trajectory.

Wonder how much fuel and ability the Service Propulsion System (SPS) would have had to respond to misguided orbits or trajectories around the moon/earth system?

ilbasso

It must have been a pretty healthy fuel supply, if you can believe what I heard as one of the abort scenarios they were initially considering for Apollo 13. I read somewhere that you could theoretically turn the stack end-forward and fire the SPS to send you back to Earth without looping around the Moon first. I've never seen that procedure formally documented in a NASA publication, though.

The process would be easier at some points in the Earth-Moon trip than others. It would be a lot easier to "turn around" when you were approaching the point where the Moon's and Earth's gravity were in equilibrium than it would be when you were just starting to speed away from Earth at 25,000 mph after the S-IVB shutdown.

Go4Launch

That engine had significant capability. Two of them could slow down the shuttle to drop out of orbit. It was also used for a Delta II upper stage.

SpaceAholic

quote:Originally posted by Go4Launch: Two of them could slow down the shuttle to drop out of orbit..

A single 21K Pound (97.5KN) AJ10-137 Apollo Service Propulsion Engine produced more thrust then the two shuttle AJ10-190 OMS engines combined. Only one would have been required for de-orbit.

quote: It was also used for a Delta II upper stage.

The AJ10-118K was used - it was a derivative of the SPS main engine but capable of generating less then half the rated thrust of the Apollo varient (about 9000 pounds).